Studio dei meccanismi della biogenesi dei cluster Ferro Zolfo

Iron¿sulfur (Fe¿S) clusters are ancient biological prosthetic groups that are essential for numerous biological processes including many enzymatic reactions that are implicated in the metabolism. In eukaryotic cells, the most common [2Fe¿2S] and [4Fe¿4S] clusters are synthesized and inserted into apoproteins by the mitochondrial ISC (iron¿sulphur cluster assembly) comprised of 17 known proteins most of which have been inherited from their bacterial ancestor. Recent studies suggest that both the components and mechanisms of Fe/S protein biogenesis are conserved from bacteria to man, making in vitro studies in the E. Coli a suitable model highly relevant for human biology since defects in this important biological pathway are now recognized as the cause of several human diseases. Among them, deficiency of the protein Frataxin (FXN) results in an autosomal recessive neurodegenerative disorder (Friedriech's ataxia) or more recently an alteration in the Fe¿S cluster assembly scaffold protein IscU was found to be implicated in a skeletal muscle disease with the development of muscle weakness. Therefore, my studies performed with the Isc operon proteins of E.Coli, are related understanding the mechanism of Fe-s cluster biosynthesis focusing especially on the connections between IscU (mutants IscUV102D and IscUI104D) and the chaperones proteins family (HscA-HscB) since their role, during the second transfer step of Fe/S biogenesis is now a days contradictory. In order to reach this purpose, many techniques as PCR, CD, cross-linking experiments, NMR Fe/S cluster reconstitution experiments and Kinetic ATPase essays were carried out allowing to get valuable evidences: the IscU structured mutants affected properties of binding to chaperones (IscUV102D with HscA and IscUI104D with HscB) causing a decrease on Fe/S cluster reconstitution rate. Instead, by kinetic ATPase activity essays, curiously IscUV102D, even if not able to bind HscA, showed an increase of HscA activity respect the control (HscA+ATP). Concluding, the obtained results could be a way forward to clear up the complex network of interactions among the isc proteins which today is far from being complete.